Fluid atomization is a key component of many industrial processes. In order to atomize fluid flowing through a pipe one may utilize what is commonly referred to as the Venturi effect, that is, the reduction in fluid pressure that results when a fluid flows through a constricted section of pipe. A common and cost effective device used to create this effect is the orifice plate. A standard single hole orifice causes a pressure drop across the orifice thereby inducing the Venturi effect which then my be used to atomize the fluid. In practice, the degree of atomization is dictated by the magnitude of the pressure drop. A larger pressure drop gives better atomization. Recent studies have indicated that new orifice geometries may be more effective in producing larger pressure changes. Fractal geometries have been studied under steady-state flow conditions but not in an orifice at the terminal end of a pipe.
The standard singular circular orifice has been in place for over a hundred years. This invention introduces a complete geometric shift in orifice design. Here we propose a new design using a self-similar multi-scale pattern of multiple orifice holes. The benefits here are two-fold: The self-similar structure of multiple holes increases the perimeter to area ratio of the effective orifice. This in turn, increases the cross-sectional area of what is referred to as the boundary layer (a phenomenon that exists in any confined viscous fluid flow) which decreases the effective area of the orifice while maintaining the same mean flow velocity. Thus a larger pressure drop is achieved for the same orifice area. On the other hand, the multi-scale design of the orifice will induce a multi-scale turbulent structure in the fluid flow. The increase in turbulent intensity further lowers the downstream pressure which produces a larger pressure differential. Hence, there are two independent physical mechanisms leading to increased pressure drop and thus better atomization.
Orifice plates having a fractal pattern have been used for metering fluid flow. The orifice plates have been used to decrease the turbulence after the orifice plate, as well as provide decreased pressure drop across the orifice plate using a fractal pattern, when compared to a pinhole orifice. There is no suggestion in any of the above-cited references that such metering plates would provide improved atomization of fluid when used at high pressure-drop conditions at the terminus of a conduit.